1. Field of the Invention
The present invention is directed to a means for drying bulk goods, particularly for pre-treatment of such goods for subsequent deposition of aluminum in an aprotic, oxygen-free and water-free aluminum-organic electrolyte. It comprises a helical vibrator conveyor for transporting the goods through a drying space containing a water immiscible liquid whereby the moisture adhering to the goods is displaced and is eliminated.
2. Description of the Prior Art
The present invention is directed to drying of bulk goods, which refers to the elimination of moisture adhering to bulk goods, and in particular, to a dewatering of the bulk goods. Such a drying has been undertaken, for example, in what are referred to as dry boxes which are heated electrically, or with gas, or with steam, the boxes having a plurality of perforated transverse walls of sheet metal lying above one another in spaced layers. Openings through which warm, humid air can be withdrawn are located at the top of the dry box. In mass electroplating of bulk goods, the electroplating devices are also frequently followed by drying means wherein the withdrawal of moisture is undertaken either by hot air or by fluorinated hydrocarbon baths supplemented with ultrasound generators.
U.S. Pat. No. 3,733,710 discloses a drying means of the type described wherein a fluid is contained in the drying space, the fluid being heavier than water and displacing the moisture adhering to the bulk goods toward the bath surface. The water collecting at the bath surface can then be withdrawn at the outside of the bath. The utilization of vibrator conveyors as the conveying element permits an extremely gentle conveying of the bulk goods, so that a jamming up of a conveyed goods is essentially prevented. Furthermore, the oscillations and vibrations occurring during the conveying of the bulk goods have a very positive influence on the drying process.
Aluminum deposited from an aprotic, oxygen-free and water-free aluminum-organic electrolyte is distinguished by its ductility, its low number of pores, resistance to corrosion, and ability to be anodized. Since access to air effects a considerable diminution in the conductivity and in the useful life of these electrolytes due to reaction with atmospheric oxygen and atmospheric humidity, the electroplating must be done in an electroplating device provided with means for excluding air. To prevent access to air during loading and unloading, the electroplating device requires inward transfer and outward transfer locks in the form of gas locks or liquid locks or as combined gas-liquid locks and equipped with conveying means for passing the goods for electroplating therethrough. For example, European Patent A 0 070 011 discloses an aluminum plating device for mass electroplating of bulk goods which operates under conditions of air exclusion and is provided with inward transfer and outward transfer locks.
Aluminum plating using an aprotic, aluminum-organic electrolyte requires a particularly careful dewatering of the goods to be aluminum plated. Thus, following a pre-treatment in aqueous baths, the moisture adhering to the goods to be electroplated must be eliminated without leaving a residue insofar as possible so that the conductivity and the useful life of the aluminum-organic electrolyte are not deteriorated. Moreover, neither atmospheric oxygen nor atmospheric moisture can be carried into the aluminum plating device together with the goods to be plated.